A disposable diaper in general use includes a diaper body having a top sheet, a back sheet and an absorbent body between a top sheet and a back sheet; a pair of side flaps positioned around the waist of the disposable diaper along a side end part in the width direction of a diaper body; and a pair of fasteners installed on an outer end part of each side flap part. The absorbent body is positioned to cover the groin region of a wearer when the disposable diaper is worn.
The above disposable diaper is worn by fitting the diaper body to the wearer in a usual method upon use, and is attached to the wearer by fixedly attaching the fastener installed on the side flap part of the diaper, around the waist on the opposite side. In this disposable diaper, it is required to fit both around the waist and legs of the wearer when the disposable diaper is worn by the wearer and to prevent liquid leakage from the leg parts and waist part while wearing a diaper.
However, for a disposable diaper where one fastener is installed on the outer end of the side flap, it has been difficult that the tensile force of the fastener is effectively concentrated around both the waist and legs of the wearer when the diaper body is worn by the wearer. That is, when the disposable diaper is attached to completely fit around the waist of the wearer, a gap remains around the legs and liquid leakage occurs from the leg region during use. Also, on the contrary, a difficulty exists in that the diaper cannot fit around the waist of the wearer because a gap remains around the waist of the wearer when attached to completely fit around the legs of the wearer.
In order to solve such problems, for example, there is a disposable diaper as described in Japanese Patent No. 3162592.
This Japanese Patent No. 3162592 installed a stress relaxation section with less tensile stress than that in surrounding parts in an area except the surrounding parts of an ear part, in the disposable diaper having one fastener installed on the area except the surrounding parts of the ear part, a pair of end edges, a centerline in a longitudinal direction and a centerline in a crosswise direction. An area extending from a part of one end edge of the disposable diaper, which is an intersecting point between the centerline in the longitudinal direction of the disposable diaper and the one end edge to the ear-part outer end part located on the side of the one end edge from an intersecting point where a first line in contact with the stress relaxation section comes into contact with the outer end part of the ear part, is provided as a first area. An area extending from a part of the ear end edge at the side of the centerline in the crosswise direction of the disposable diaper to the ear-part outer end part located on the side of the crosswise centerline from a point where a second line in contact with the stress relaxation section comes into contact with the outer end part of the ear part, is provided as a second area. Provided is the disposable diaper having a fastener attached to a location that can effectively and directly concentrate the tensile force of the fastener around the legs and waist of the disposable diaper by attaching the fastener to overlap on at least a part of the first side edge area and a part of the second side edge area (Japanese Patent No. 3162592).
However, in such a conventional disposable diaper, the stress relaxation section with less tensile stress than the surrounding parts is poor in fitness to a body of the wearer and a gap remains. Also, installing an emboss, slit, aperture or the like which is a means of stress relaxation has undesirable effects on the wearer, such as bad contact with skin and poor aesthetics. Also, inconvenience exists such that the first side edge area where the fastener is not joined is defectively turned up while wearing a diaper since the stress applied to the fastener upon wearing is not conveyed.